Purification and bleaching of waxes



UNITED STATES PATENT OFFICE 1,980,338 PURIFICATION AND BLEAOHING 6F WAXES Arthur Hough, Passaic, N. J., assignor to Theodor Leonhard Wax Company, Haledon, N. J., a corporation of New Jersey No Drawing. Application August 17, 1931,

Serial No. 557,727

2 Claims. (Cl. 87-19) The present invention relates to certain very having previously placed in the tank about 750 important and valuable discoveries relating to he pounds of water (corresponding to about Onepurification and bleaching of waxes, and pa fourth of the weight of the wax). In order to ticularly beeswax. Actual use of the process as preserve this ratio of water to wax during the proven it to be highly economical and very pra treatment, I prefer to heat the mass by means of tical. closed steam coils. The water and wax are heated The invention will be described in detail in its up to a temperature preferably about 90 to 95 0'. preferred form, in connection with beeswax, but (say 93 C.) i. e. a little below the boiling point it is applicable also to carnauba wax and, I beof water. I add the dilute crude phosphoric acid 10 lieve to various others. mentioned above, in amount equal to about 2% I have found that phosphoric acid, either the (for example) of the wax (=0.6% actual H3PO4 ortho or the meta compound has a very useful based on the wax), and stir vigorously, by one action on the wax, completely removing many imof the types of motor driven stirrers known-as purities, both those in plain suspension and those lightning mixer, whereby a most intimate mix- 15 held in a colloidal condition. The impure Wa ing of water and acid and wax is obtained. The melted and subjected to the influence of ph sinitial mixture of water and acid i. e. 60 pounds phoric acid becomes clarified in a manner qu te of the crude dilute acid in 750 pounds of water impossible of attainment With y other c represents approximately a 2.4% solution of which has heretofore been used. I am aware that H3PO4. The mixing should proceed for about 10 20 in the past, sulphuric and hydrochloric acids have minutes, at about 90 to 95 0., when the stirring is been tried for this purpose, and while they clarify stopped and the tank may be covered up (to prethe wax better than plain settling over water, the vent rapid cooling) and allowed to stand for wax having been melted and stirred with the Waeral hours, when the wax will be found to be ter, yet I have found that the results obtainable completely clarified. All suspended and colloidal by the use of phosphoric acid are so far uperior matter will have been removed, and thrown to the than anything obtained by prior methods, as to be bottom of the wax and largely into the acidulated revolutionary. water, the wax will be found to be what is known I have u d during my s c s d in as pure refined wax, and of a clear, almost transtual plant practice, that the variety of ph sphoric parent character. This remarkable efiect can be 39 acid known as crude is better for my P pos obtained by the use of, very little of the phos- 35 than the chemically pure acid, one particular phoric acid, and as stated above, the crude acid sample of this ude p sp ric acid yzi actually works better than pure HaPOi. This as follows: may be due to the coagulating efiect of the iron,

aluminum and other salts (impurities) dissolved P 0 5 33 in the crude phosphoric acid, these salts will be E l-5 t H31904 1 v I 29:18) found, together with the impurities of the wax, in 1 0 64 the water under the clarified wax. Some of the F820; 92 impurities may be in the bottom layer of the wax. 0 a" 69 Most of the molten wax can now be decanted 40 Geo u I 93 in a bw i tmihdand til; bottom laylierdof the 95 wax can e re rea e or o er pm 8 Orgamc mammal n In this example I have referred t the use T is a y s c ve s an a e ade of crud of 60 pounds of the crude phosphoric acid in the P p r c acid just as it is obtained from the treatment of a particular grade of wax. In other 45 decomposition of Phosphate milk, and Without cases I have used much less, say 25 or 30 pounds any further purification. This gradeis of ou e of the acid (with 3000 pounds of wax and 600 to of the lowest market value (1. e. is the cheapest, 800 pounds of water) while securing very satisfor a given amount o actual HQ OO and is factory results. These variations would corretherefore v y economical to use for the p ese spond to acid concentrations of about 1 to-nearly 50 purpose. This is given merely of a highly suit- 4% able P o p acid, t the invention s v In commercial practice after treatment with limited to acid of this analysis. phosphoric acid, and stirring, the wax begins to A a example of the process of purifying the clear immediately, the impurities settling down crude w x, I i h ing as an illustration: through the bulk ofwax towards the bottom. It I 55 I melt 3,000 p un o the in a e tank left to settle long enough, the impurities will all 110 go to the very bottom of the wax, appearing as a spongy matter, with such inorganic substances as may be present and of a higher specific gravity than wax or water, going to the bottom of the vessel. In practice at the works, I allow the wax to settle over night as a matter of convenience. The wax may be treated at about 4 P. M. and then covered up. .The tank being of very thick wood, when covered, I find the wax and waterwill hold the heat till the following morning, when operations commence. Thus I may allow the wax t6 stand therefor a. matter of about '15 hours, although'perhaps the settling is complete in much less time.

Bleaching the wax.The clarified wax, is now ready to be bleached. This may be done by way of example in'an apparatus as follows: A wooden tub, measuring about 50 inches diameter, and 60 inches high (inside measurementslis fitted with a powerful stirrer. This stirrer may conveniently be of the turbo type of impeller, inches in diameter having 12 blades placed at an angle of about 30 degrees. This stirrer can be fitted on a steel shaft 2 inches in diameter and covered with lead to a point as high as the top of the tub. The stirrer itself may be cast in one piece of antimony-lead alloy (preferably 5% antimony and 95% lead). The shaft is held in I bearings some distance apart to give rigidity to the driving equipment.

The shaft revolves at about 150 revolutions per minute, the action of the stirrer being preferably downwards to ensure perfect agitation or dispersion of the liquids. Obviously this apparatus is given merely by way of example.

About 1000 pounds of water (ordinary tap water will do), are placed-in the tub, heatedto H about 65 C., and about 160 pounds of the crude dilute ortho phosphoric acid added, the stirrer is started and a few seconds mixing given. This gives a dilute phosphoric acid solution of about.

4.7% strength. Then 1250 pounds of the clarified beeswax is. added, this latter at a temperature of about C. This represents about 3.8% of actual H3PO4 relatively to the wax. The wax,, acid and water are now stirred continuously and into the mixtureis run. a solution of 50 pounds of potassium permanganate in 300 pounds of water at about 'C..which has been slightly acidi-' fied by-HaPoi. The bleachingaction starts immediately,'an d is allowed to proceed until the end point of the bleaching is reached. This point is ascertained by testing the mixture in the following manner. Asample is dipped from the tank and allowed to stand inabeaker for a fiew minutes. If the end point isreached, it will be found that the clear wax will rise to the top, the oxides of manganese (product of reduction of permanganate) will fall to the bottom, and an intermediate zone of a pinkish solution will be apparent. If the endpoint is not reached, it will be seen that the wax does not separate well, and

- the process must be continued till such time as another similar -test gives the desired result.

When' treating beeswax of average grade, this may require. about an hour. When such end point is reachedithe charge, in the tub should be allowed to settle fora few minutes, when the bleached wax will be ready to be removed from the mother liquor. The latter is still acid in reacof the tub, the wax flowing into a wash tank placed at the side of the bleach tub. This wash tank contains water, acidulated with H2804 to an extent of about .1%.

- I have referred in this example to temperature at which the mixture of wax, acid, permanganate and water should be at the start, about 65 C. To explain this, point. The important'point to look to is the maximum temperature to go to dining bleaching, and for the very best results, I have found this maximum temperature should not exceed C. Now, in order to determine the temperature at which to start the process to reach this temperature, we have of course to consider the following:I-Ieat of reaction (KMI104 oxidation valueor organic impurities in wax), specific heats of wax, water, and acid, and weights of same. In actual practice I find that in wood tubs where radiation factor is low, I can start I with the mixture at about 65 C. At the same time, it must be remembered that in the case of a wax such as a very high grade of Chilian beeswax, or light Cuban beeswax, the organic impurities are so small that much less mm is required and consequently less heat of. reaction develops. In such a case, the charge may be as high as 70 C. at the start, and it will not exceed 80 C. at' the finish. The pilot laboratory test will determine this point. Another thingof importance. A' charge should always be allowed 0 to proceed under its own' heat of reaction. There is a cu'rious'phenomenon in this connection. If a bleach is in progress, and;the' temperature be checked by any. method of cooling, and then raised again by heat fromclosed or open steam or hot water coils, the bleach is not good. The charge, starting at the low temperature should, be allowed to find its maximum temperature by its-own heat of reaction. This hasbeen shown in commercialruns. a

The time required to effect a bleach, after all ingredients are in the tub and stirrer started, ,is generally about one hour. This however may vary according to the grade of wax.

The object of this acidulation, will be explained later; It is important to have this wash water slightly acid, if it is not, good results are difficult to obtain. The wax being now i'n the slightly aeidulated water, best at about?" 0* C., by means of a rapid stirrer (such as was for the clarification of thecrude wax) the wax is given a thorough washing for example at about 80 C. for say 15 minutes. This maybecalled the "prewash and is.'-very important. After this prewash, the wgi allpwed to' settle, and the wash water is then rynp if by means of a cock at the bottom of thewash tank; Then another lot of water, slightly acidulated with H2804, also at about 80? C. is run in, and about'two pounds of 93% H2304 is added, this acid should be diluted to 20% or less, before addingtothe wax and water, as strong HzsOi coming into contact with the bleachedwax mayafiect its color. Brisk agitation is now continued and about three pounds oflOO-volumehydrogen peroxide added.

If 25-volume H2O: is used, then proportionately more of, it must be added. It will be found after 15 minutes stirring, that the wax has assumed a flne white color and need. only be allowed to settle, the acid water drawn oil, and another hours when the white wax may be drawn off My idea of hydrogen when washing bleached wana tap at the side of the tank, or preferably by displacement as described above, and this wax is now found to be highly bleached. i

The wax may then be given one or more additional washings with distilled water, (preferably at about C.) the object of which is to remove all (orsubstantially all) acidity, without running any risk of any alkaline reaction. This would be an advantageous addition to the process, if a supplyof distilled water is available, but many commercial runs, without the washing with distilled water have given'very satisfactory results. This wax which preferably has been kept molten throughout the treatment, can then be run into molds, and allowed to solidify by cooling.

In the several washings, I preferably use a temperature about 80 C. this procedure should be followed in all washing operations. At about this temperature, the wax is very fluid and agitates and washes better than if at a lower temperature. It is inadvisable to heat to a higher temperature, although no great amount of harm will result. It must be kept in mind that when beeswax is bleached, it is easily thrown ofi a shade or so in color by too much heating, so it is better to keep it at a reasonable temperature, and to avoid temperatures much above 80 C.

While I have given proportions and quantities, in the spec fic example, which are highly satisfactory, I do not limit thee invention to these, since the same can be varied between rather wide limits, without departing from the inven-' tion. These figures show the preferred amounts when the crude wax is of average grade of purity; When a more impure-wax is being treated, I would preferably use somewhat larger amounts of the chemicals even up to double the amounts given above, or even somewhat more, and the amount of water can remain as given above. Similarly when using a crude wax less impure than average grade, less of the chemicals can be used, even down to half the amounts above given.

The amounts of water given in the several chemical treatments can also be varied between wide limits, but the quantities stated above will be found very satisfactory.

It is important to place the phosphoric acid the water in the bleach tank before running in the crude clarified wax. If this is not done, the natural alkalinity of the water may emulsify the wax, and this, whilst not very serious may easily prevent subsequent separation for some time, and thereby delay the process. It is very important (as has been found in commercial tests) to acidify the permanganate solution with phosphoric acid before running it into the wax. If the permanganate is not acidified, but run on to the wax even when this is mixed with the phosphoric in the bleach tub, there may be a local alkalinity arising at the instant the KMIDO; solution strikes the wax, which may cause an emulsion, which would delay the process.

If this water in the washing steps be not acidified before the wax is run' into it from the bleacher, the wax carrying practically no acid from bleacher, striking the large volume of water of ,natural alkalinity, this alkalinity has the well When'the wax is passed from the bleacher to the wash tankit may and generally does 7 carry a minute quantity of permanganate of potash and also a trace of the oxides of manganese in suspension. H202 in this case acts as a reducing agent, immediately reducing both these reagents to the lowest. oxides of manganese, and

has beenbleached, it ill contain iron and manganese salts and probably other salts present in the reagents at the start. The pre-wash is to remove such salts, which it does most effectually and the acid present of course prevents such salts being acted uponby natural alkalinity of the water which would have the effect of fixing the iron and manganese in the wax, and imparting to it the characteristic color of manganese and iron on organic matter. Wax, like cellulose, has a great aflinity for these substances.

Heretofore processes of bleaching wax and particularly beeswax depended on the use of oxidizing agents, such as'chromic acid, bichromate potassium or sodium and sulphuric acid, permanganate of potash and sulphuric acid, perborate of soda and many others, are well known but the performance of these reagents is utterly different from the action of phosphoric acid, and do not give comparable results.

When H2SO4 is used with KMnOr for bleaching wax, by certain processes previouslysuggested, the acid to sufficiently decomposethe KMnO4 has to be of such strength as to actually attack some components ,of thewax, injuring its quality. -The action is so violent as to produce violent frothing in the'bleach tub. As an instance of this I may state that in a bleach tub. of the dimensions given above, only 600 pounds of wax could be used in a charge, by the old way (KMnOr plus H2804), due to frothing. By the new way charges of 1250 pounds are regularly run, in this tank without any sign of frothing.

Phosphoric acid is the one acid that (within the the prior art. Moreover, a large portion of the phosphoric acid may be recovered and used over again as it undergoes no change during the process, and the manganese oxides may also be largely recovered and marketed or reworked into KMn04. To sum up this new process of firstly clarifying the crude wax, by treatment with phosphoric acid and then bleaching by this new process it is believed to been important, advance in the industry. J

I have found that the crude andimpure phosphoric acid is not only superior to'the pure acid in the pre-treatment process;, but also in the actual bleaching process. I am using and prefer to use, the crude acid with permanganate. The iron, aluminum and calciumcompounds in,the

.crude phosphoric acid (all of which are soluble,

to some extent at least), may have some useful effect in the process.

I have referred above to the use of permanganate. Other 'permanganates such as the sodium compound, canalso be used.

potassium say 80 C. In this way, the phosphoric acid may.

If it is desired to recover" the phosphoric acid in the displacement step without dilution, then in place. of the hot water mentioned for raising the level of bleached wax, some of the phosphoric acid from a previous bleaching run may be employed for this purpose, this preferably being hot,

be used for several cycles, before it is unfit for use. To start this cyclic operation, of course enough phosphoric acid must be on hand for the displacement of the bleached wax of the first batch, but after this, there will be plenty of the acid from previous runs to carry on. Great economy results from this procedure, as for several cycles only the mechanical losses of acid have to' the bleaching is sufliciently accomplished;

be compensated for by addition of fresh acid;

I claim:

1; A processof treating vegetable and/or animal wax to purify the same, which comprises agi-.-

tating the wax while in contact with hot water,

with phosphoric acid of about 1 to 8% strength, said acid containing soluble iron and aluminum compounds, at not considerably above the normal boiling point of water, then settling and separating the aqueous liquid and impurities and-the refined wax from each other.

2. A process of bleaching wax which comprises treating the molten wax with an acid mixture comprising a permanganate and, phosphoric acid and being diluted with many times its own weight of water, while warm, and'containing soluble iron and aluminum compounds, and agitating until ARTHUR HOUGH. 

